In general. Except as provided under Subsection (b), below, upon a lease renewal or execution of a new lease, a landlord shall not increase the rent of a regulated rental unit to an amount greater than: the base rent; plus the rent increase allowance under Section 13-144; plus any banked amount (the manner of application and determination of a "banked amount" shall be established by rent stabilization regulations adopted by the Director and shall include a requirement that the applicant fully compensate the County for any costs the Director determines are associated with determining whether the applicant meets the requirements of being able to utilize a banked amount); and does not exceed 10 percent of the base rent. Limited surcharge for capital improvements. Subject to Subsection (c), below, the Director shall grant a landlord's petition to add a surcharge to the amount permitted under Subsection (a) if the Director determines, in accordance with rent stabilization regulations adopted by the Director: the surcharge is limited to an amount necessary to cover the costs of capital improvements to the regulated unit, excluding the costs of ordinary repair and maintenance; the surcharge does not take effect until after the capital improvements are completed; if the capital improvements are for all rental units within the building, the surcharge: is divided equally among the units; is prorated over at least 96 months; and does not exceed 20 percent of the base rent; if the capital improvements apply only to certain regulated rental units within the building, the surcharge: is divided equally among the affected units; is prorated over at least 60 months; and does not exceed 15 percent of the base rent; the surcharge for each unit ends once the costs of the capital improvements, including any interest and service charges, have been recovered by the landlord; the capital improvements would protect or enhance the health, safety, and security of the tenants or the habitability of the rental housing, provided that the purpose of the capital improvements cannot be to address code or other habitability violations. Notwithstanding the foregoing, a new owner may apply to the Director for a waiver to authorize the inclusion of limited surcharge, as provided in this Section, if the capital improvements would result in energy cost savings: the savings would be passed on to the tenant; and either: the improvements would result in a net savings in the use of energy in the building; or the improvements are intended to comply with applicable law; the capital improvements are depreciable under the federal Internal Revenue Code; the applicant has certified to the Director the costs of the capital improvements, including any interest and service charge; the applicant has certified to the Director that required governmental permits and approvals have been granted; and the applicant fully compensates the County for any costs the Director determines are associated with determining whether the applicant meets the requirements of this Subsection. Surcharge — additional requirements. A landlord must maintain, and must make available to a tenant with an active lease for the affected unit or the Director upon request, all plans, contracts, specifications, and permits related to any capital improvements for which a surcharge has been granted. Immediately upon the completion of capital improvements under this Section, a landlord must permit the return to affected rental units of any tenant with an active lease for the unit who was displaced due to the improvements.